code: def is_data_placeholder_list(l):
      return all([isinstance(item, DataPlaceholder) for item in l])
  
file_path: baikal/baikal/_core/data_placeholder.py
imports: from functools import total_ordering
  from baikal._core.utils import make_repr
label_desc: Use image node_id 1 for calling a global function with example usage: is_data_placeholder_list(l) and returns: all